1. Field of the Invention
The present invention relates to an auto-closing device, and more particularly to an auto-closing device for a sliding door to provide an adjustable spring pulling force applied to the sliding door.
2. Description of Related Art
A sliding door panel always has an auto-closing device having a buffering effect to pull the sliding door panel to an original position. A conventional auto-closing device has a spring, a buffering cylinder and a moving element connected to the spring and the buffering cylinder. The moving element can clamp a connection rod mounted on the door panel and moves with the door panel to an opened or a closed condition. The spring provides a pulling force to the door panel to move the door panel to an original position. The buffering cylinder provides a buffering effect to the door panel to prevent the door panel bumping with a door frame and to cause the damage to the door panel.
However, the pulling force provided by the spring of the conventional auto-closing device is not adjustable and is constant, the conventional auto-closing device cannot be applied to different door panels with different weights. When the conventional auto-closing device is applied to a door panel having a light weight, the pulling force provided by the spring is too large to pull the door panel. Thus, the moving speed of the door panel is increased to cause a large bumping force applied to the door panel. In addition, a large force is necessary for a user to open or to close the door panel for overcoming the pulling force of the spring, the conventional auto-closing device is inconvenient in use. When the conventional auto-closing device is applied to a door panel having a heavy weight, the pulling force provided by the spring is not sufficient to move the door panel to the original position.
To overcome the shortcomings, the present invention tends to provide an auto-closing device to mitigate or obviate the aforementioned problems.